inet: fix NULL pointer Oops in fib(6)_rule_suppress
This changes ensures that the routing entry investigated by the suppress
function actually does point to a device struct before following that pointer,
fixing a possible kernel oops situation when verifying the interface group
associated with a routing table entry.
According to Daniel Golle, this Oops can be triggered by a user process trying
to establish an outgoing IPv6 connection while having no real IPv6 connectivity
set up (only autoassigned link-local addresses).
Fixes: 6ef94cfafba15 ("fib_rules: add route suppression based on ifgroup")
Reported-by: Daniel Golle <daniel.golle@gmail.com>
Tested-by: Daniel Golle <daniel.golle@gmail.com>
Signed-off-by: Stefan Tomanek <stefan.tomanek@wertarbyte.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 523be38..f2e1573 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -104,7 +104,10 @@
static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
{
struct fib_result *result = (struct fib_result *) arg->result;
- struct net_device *dev = result->fi->fib_dev;
+ struct net_device *dev = NULL;
+
+ if (result->fi)
+ dev = result->fi->fib_dev;
/* do not accept result if the route does
* not meet the required prefix length